Sharp SF-1120 - Manual (Page 35)

(20) Original size sensing
The original size is sensed by the original interruption system.
The LED in the rear frame side emits light to the table glass surface.
The original interrupts this light, and its size is detected.
2. Basic operations
(Positions of the original, the lens, and the image in each mag-
nification ratio)
Normal: The distance between the original set on the table glass and
the lens is equal to the distance between the lens and the
drum, resulting in the equal size of the original and the
image.
Enlargement: Compared to the normal copy, the lens is nearer to the
original and the distance between the original and the
lens is shorter.
The distance between the No. 4/5 mirror unit and the
lens is greater, and the distance between the lens and
the drum is also greater.
The distance between the original and the exposure
surface of the drum is greater than that in the normal
copy.
Reduction: Compared to the normal copy, the lens is nearer to the
drum, and the distance between the original surface and
the lens is longer.
The distance between the lens and the exposure surface
of the drum is shorter.
The distance between the No. 4/5 mirror unit and the
lens is greater.
The distance between the original and the exposure sur-
face of the drum is greater than that in the normal copy.
(Copy lamp control in each copy density)
Execute Sim 46-01 to determine the copy lamp application voltage
(CLV) in EX1 and EX5.
Then divide the difference between the voltages of EX1.0 and EX5.0
into nine.
The application voltage of the copy lamp in each exposure level is
determined by varying the ON timer duty of the copy lamp ON control
signal.
• Photo density copy mode
Make the same control procedures as the manual density copy
mode.
The image density is controlled by lowering the grid bias voltage of
the charging charger. To maintain the reproduction quality in half
tone, the ON time duty of the copy lamp ON signal is made shorter
than in the manual density copy mode. (The application voltage is
lower.)
Table glass
Light emit
Light receiving
Mirror base scan speed
Copy paper
feed derection
Lens and mirror positions
are changed to adjust the
magnification ratio
Mirror scan speed is cahnged to adjust the magnification ratio
Mirror scan speed Drum rotation speed
Enlargement
Original
Reduction
CLV
80
70
60
50
(V)
EX1 2 3 4 EX5
[MAX. 83V(166V)]
[MIN. 45V(90V)]
40
(Copy lamp
application
voltage)
5 – 6